#include <bits/stdc++.h>
using namespace std;
int main(){
    freopen("duel.in","r",stdin);
    freopen("duel.out","w",stdout);
    int n, a[114514];
    cin>>n;
    for(int i=0;i<n;i++){
        cin>>a[i];
    }
    printf("%d",n/2);
    return 0;
}
